If you are seriously considering doing this job.... You need to make enough in contract to at least by a larger heavy duty skid steer or a back hoe. There is no way around it... Im unfamiliar with your area and how much snow you get.. But im from wyoming and even our smallest snow storms... with a mall about your size would be the end of me. Two plows will not do it not only for the individual storm ... but you can't expect a plow to last that many miles in a season. And what happens if one goes down??
The mall probably has a large budget for this kind of work... relatively speaking. I almost got a job this year plowing at a home depot, turned it down in the end but it paid 45k a season! That sounds like a lot ... but it would have required equipment where my access is sort of limited. I hope you can make this work... but don't kid yourself on it. Charge what is fair and keep in mind that you are going to HAVE to buy new equipment in order to succeed. May be a good business opportunity however..